If image processing is to be undertaken for recorded medical images, for example for x-ray images, at least part of this process is software-based. The algorithms necessary for image processing are thus, at least in part, implemented in software, with the software being executed on a so-called high-end medical computer system, also known as a workstation.
On the medical workstations (e.g. in the cardiological and angiographic environment) two processes which demand a high level of resources and computing power are preferably carried out on the image data originating from the recorded images:    1. nD rendering (multidimensional rendering or image synthesis)    2. Reconstruction of volume data
Since rendering is a very memory-intensive operation, it is primarily a GPU-based process (e.g. on a graphics card). Ever faster GPU processors and larger storage capacities are being provided on new-generation graphics cards.
Reconstruction involves an operation which is to be carried out very quickly and contemporaneously, since the computation operations of the reconstruction are to be carried out where possible directly after or during the acquisition of the image data needed. A delay between acquisition and beginning of reconstruction is inconvenient during an operative intervention.
Whereas a graphics card which has a very high storage capacity (to avoid what is known as swapping between GPU and main memory)—as described above—is used for the rendering, a further card compatible with the graphics card is used for reconstruction, which is designed to fulfill the intensive computational requirements of the reconstruction. For example a so-called PCI (Peripheral Component Interconnect) card can be used for this purpose.
FIG. 1 shows an example of such an image processing system Sy. It features a central processing unit CPU, which is connected to a storage unit St, to an input interface I-IF for a data input I and to an output interface O-IF for a data output O as well as to a graphics card GC, on which one or more GPU processors can be arranged and to a PCI expansion card PCI.
Accordingly the rendering is carried out in the example on the graphics card GC and the reconstruction on the expansion card PCI.
This method of operation is uneconomical, since costs for a high-quality graphics card with a high storage capacity as well for an expansion card suitable for the reconstruction must be incurred.
A further disadvantage lies in the fact that with PCI expansion cards a part implementation of the algorithms is often also necessary in hardware or firmware (for example with the algorithms for many C-arm x-ray systems). In this case the number of PCI expansion slots in the workstations for image processing, which usually involve standard PCs, is restricted.
Because of the serial data flow in image processing, the cable already defines the data flow, but also whether the algorithms are to be implemented in hardware or software. This means that the sequence in which the algorithms will be processed is largely defined. The structure of the image processing is thus rigidly predetermined. The consequence of this is that the PCI expansion card provides practically no interfaces for future computer generations, which results in further costs for a comparable expansion card when the workstation is replaced.